The ideas behind the books

Into a Parallel Universe

It can happen, in books. One minute you're walking along the road minding
your own business, next minute you've passed into a parallel universe, and
things can only get better, or worse. It's a bit like the literary concept of
time travel, except that a parallel universe can be even more outlandish and
difficult to explain.

In Philip Pullman's book 'The Subtle Knife', Lyra says:

' ... No one can count how many worlds there are, all in the same space, but no one could get from one to another before my father made this bridge.'

Now, how can they all be in the same space? Worlds are made up of matter. Where is all that other matter?

The only way I can come to terms with millions of other worlds is by
accepting that there are millions of other people and each person perceives a
different world, but I don't think that is what Lyra means. On the other hand,
when Lyra visits the museum in Will's world she sees the very same sledge that
she had been carried on when she was kidnapped by the Samoyed hunters:

And even that rope had frayed and been re-knotted in precisely the same spot, and she knew it intimately, having been tied up in that very sledge for several agonizing hours ... What were these mysteries? Was there only one world after all, which spent its time dreaming of others?

I don't understand this. Philip Pullman's worlds apparently all sit on top of
each other. Has the sledge 'dropped through the floor' from Lyra's world into
Will's? Obviously, Dust drifts freely around through all the universes, so
perhaps other things do. Lyra and Will manage it after all, don't they?

Perhaps in His Dark Materials Philip Pullman's point is that it is only through sheer, blind chance that we
have evolved into what we are today. In countless other worlds, with countless
other chance happenings, countless other species could evolve. Take the mulefa,
for instance.They are conscious beings, with religious sensibilities, but
they are four-leggety-wheeled beasties. And yet, despite the randomness of
evolution, conscious species all develop some sense of God and Heaven.

Alas, I suspect there is no such thing as a parallel universe such as
Philip Pullman describes. But I do think it's quite easy to walk into a real
parallel universe. They're all over the place. Try spending the afternoon in any
enclosed institution - school, for instance, or hospital, or your father's
office, or a travelling circus - you can become so involved in the detail of
what is happening that if you suddenly look up and out of the window you can be
quite surprised to see 'ordinary life' going on in the street outside. Worlds
within worlds.

Have a look at Philip Pullman's 'His Dark Materials' trilogy if you're interested in parallel universes.